Building my own sawmill

[tuolumne]

How about a valve with a priority circuit.

The priority circuit could power the band saw, and the excess flow would power the track.

https://www.surpluscenter.com/item.asp?item=9-4158-5&catname=hydraulic

Thank you. I obviously have much to learn since I did not know these existed. However, people build sawmills; I'm a person...

 

[tuolumne]

I think you should look into a, straight from PTO, mechanical powered cutting unit. Run the rest off hydraulics. That way you can focus maximum power where it is needed the most, the cutting.

If you are still planning on hydraulic cutting, I would advice dual pumps, one large for cutting and one smaller for the rest...

PTO power=stationary cutter and moving log. This means a carriage roughly twice as long which is more material, more site prep, less portable etc. I agree, it seems simpler. Saws in the size range that I am using typically have dedicated gas engines in the 10-20 HP range. You think the hydraulic pump on this tractor can't output that much?

 

[tuolumne]

Pressure will constant, flow is basically linear. So at 1/2 of the rated PTO RPM you'd have about 4.3 GPM.

My gut felling is that you will not have near enough flow to properly power this machine.

If you really want to power it hydraulically, then use a PTO powered pump and keep it isolated from the tractors system. That is the way these Hakki Firewood Processors operate, a friend of mine has one.

A PTO pump would be a simple solution if tractor hydraulics are not up to it. However that's another $500 component in the system.

With the size of band wheels that I'm planning, pully size etc. I need about 340 rpm from my hydraulic motor for proper band speed. That's around a 3 cubic inch/rotation pump if my tractor can dedicate 4 gpm to the band. The missing link in my mind is how tractor horsepower (in my case 37) translates to output HP in the hydraulics.

 

[AKKAMAAN]

PTO power=stationary cutter and moving log. This means a carriage roughly twice as long which is more material, more site prep, less portable etc. I agree, it seems simpler. Saws in the size range that I am using typically have dedicated gas engines in the 10-20 HP range. You think the hydraulic pump on this tractor can't output that much?

Tractor will out put the max rating of flow and pressure combined....

at every 2000psi - 10gpm makes 11.6hp, and 2000psi - 15gpm makes about 17.5hp..
what is your pump flow at engine rpm rating and what is the max system pressure in your tractor?

Reason you want to isolate cutter power from the rest of hydraulics is that cutter is going to run continuously, and you do not want the rest of hydraulics put "distortion", like temporary pressure drops and flow drops, in to cutting power drive line...also diverting flow (flow divider) into a cutter circuit, really creates a lot of power losses (heat) in system. This also the main reason mechanical drive is to prefer. Running a continuous high power hydraulic motor, will waste at least 20-30% power between pump and motor while cutting.

 

[J_J]

Are you talking band saw or blade. Why not use a dedicated engine like a 20 HP Honda or Kohler. You could walk it down the track or power it down the track with hyd motor.

 

[tuolumne]

Are you talking band saw or blade. Why not use a dedicated engine like a 20 HP Honda or Kohler. You could walk it down the track or power it down the track with hyd motor.

I can see where HP loss and heat could be an issue. I am building a band saw. The nice thing about hydraulics is it would be simple to shut off the band at the end of each run. A PTO drive would require some kind of clutch system, as would a dedicated engine. I want to avoid the expense and maintenance of another engine while I have a tractor.

PTO pump= 37 hp at the PTO so more hydraulic flow potential. Parts = PTO pump, band motor, priority cirucuit, drive motor, hoses, log turning hydraulic piston, control levers. A pro would be hydraulic controls, and fairly easy to detach to move more logs around with the tractor.

Tractor hydraulic pump = Less flow, possibly too little (8.6 gpm and 2500 psi at rated RPM). Parts = band motor, priority cirucuit, drive motor, hoses, log turning hydraulic piston, control levers. This is one $500 part less than the obove scenario. Also would be easy to disconnect. Does the tractor have any priority circuit? For example, I could run the band off the power beyond (backhoe) hydraulics and the other controls off of the 3rd SCV valve. Would this cause a pressure/flow drop in the primary system?

PTO direct = 37 HP available with more power transfer (overkill, but I would like to run at lower RPMs anyway for fuel and noise) This means a stationary cutter head which seems less ideal. Parts would be a gearbox and some kind of clutch system. I would still need hydraulic lines, a drive motor, controls and a piston. This is the gearbox and more sophisticated carriage versus the cost of a PTO pump and drive motor with priority control of the first option. I'm not sure what would cost more.

Dedicated engine = like everybody else does it. Expense is engine, clutch, fuel tank + mounting. It would be a lot noisier. I still need the hydraulic components for a log turning piston and carriage drive motor.

 

[kennyd]

Does the tractor have any priority circuit? For example, I could run the band off the power beyond (backhoe) hydraulics and the other controls off of the 3rd SCV valve.

Short answer=No. You really don't have enough to work with here...I still say a PTO pump is the only solution for you to hydraulically run the mill. It also keeps the two systems separate for maintenance issues.

 

[Egon]

Consider talking to your tractor dealer for the hydraulic capacities.

The blade power required should be a variable based on log size, log type, condition of the wood, grain orientation and feed rate. Changing feed rates may be a required option in some circumstances.

It would be assumed you are also using the tractor to load in the logs. If that is the case a hydraulic system may be easier to hookup and unhook.

 

[J_J]

tuolumne,

Have you looked at all the videos on You Tube. Most of them use a dedicated engine for the band saw. There is no reason to shut off of slow the engine on the return operation, besides that, if you power the track with hyd, you want the pump running at max for a swift return. It would not be logical to slow of stop a hyd driven band saw on the return stroke, as a hyd motor needs to slow down gradually, and requires a motor spool valve with relief.

You are going to have noise with any engine be it tractor or dedicated engine, unless you use electric band saw motor, and electric track drive.

 

[tuolumne]

I have decided to explore the PTO direct drive option with a moving log carriage. I will probably be asking some new questions in a forum other than hydraulics at this point. Thanks for the insight.